Modern magic lanterns; a guide to the ... - Yesterday Image

100 MODBEN MAQIO LANTEBN8.tions it can be replaced by a slightly modified form ofcompound microscope, which is attached in front of thecondenser of the usual lantern. In Fig. 72 a simple formof compound microscope is shown, which can in a fewmoments be removed from the stand on which it has servedas a table microscope and placed on the lantern nozzle,as shown in the top right-hand figure. The objectives ofvarious powers can be slipped into the racked mount, thosemost commonly supplied being 1- and 2-inch powers. Anadditional lens as a supplementary condenser is sometimesfitted between the chief condensers and the object,and when properly adjusted this much improves theillumination.The real difficulty in microscopic projection has alwaysLantern micro-been the proper illumination of the object.scopes cannot be expected to yield as bright images on thescreen as ordinary lanterns showing slides vrith but a fractionof the magnification. In consequence, the operator's attentionshould be given to the proper adjustment of the light and condensers.The light concentrated on the small surface of theslide will soon make it very hot unless prevented by meansof an alum trough (see p. 84) ; this in micro-projection shouldnever be omitted, or it will lead to the ruin of the slides.The sUdes in the simpler forms of lantern microscope arefitted in wooden frames like ordinary lantern slides, onlythese frames are smaller. Frames can be obtained one endof which takes out to receive the usual size of microscopeslide, for use in the lantern. These are a convenience, butit is decidedly preferable to have a microscope attachmentwith the usual form of plain sliding stage, so that the slidescan be used direct without any further mounting. This isthe case with the instruments shown in Figs. 72 and 73.Too great a degree of magnification should not be attempteduntil the management of the lantern with low powers hasbeen thoroughly mastered. A 1-inch objective will' befound the most powerful which can be used in the ordinaryway with satisfactory results, both as regards illuminationand other quaUties. On changing the objective the positionof the jet should be altered until the best fighting is secured,as it will be found that lenses of different powers require the